1. Field of the Invention
The present disclosure relates to electrical machines, and more particularly to electric slip rings with built-in resolvers for synchronous machines and doubly fed induction machines.
2. Description of Related Art
Synchronous machines like synchronous motors, synchronous generators, and synchronous motor/generators typically include rotors and stators. The stator of a synchronous motor typically receives alternating current and rotates the rotor in synchronization with the frequency of the applied current. A prime mover typically rotates the rotor of a synchronous generator such that the stator outputs electrical current from the stator with a frequency corresponding to the rotor rotation frequency. Synchronized motor/generators typically operate as either synchronous motors or synchronous generators depending on the received input.
Synchronous and doubly fed induction machines generally include rotor position sensors and exciters. Rotor position sensors report the angular position of the rotor for purposes of controlling operation of the machine. Exciters transfer electrical power between the machine stator and rotor, generally through a slip ring or rotary transformer. Slip rings typically transfer electrical power through physical contact between the stator and rotor. Rotary transformers typically transfer electrical power without physical contact between the stator and rotor. Such electrical machines have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved systems and methods for detecting rotor position and for transferring electrical power between rotors and stators. The present disclosure provides a solution for this need.